Formulas

Ions Cation: A positive ion Mg2+, NH4+ Anion: A negative ion Cl-, SO42- Ionic Bonding: Force of attraction between oppositely charged ions.

Predicting Ionic Charges Group (IA) 1: Lose 1 electron to form 1+ ions H+ Li+ Na+ K+

Predicting Ionic Charges Group (IIA) 2: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+

Predicting Ionic Charges Group (IIIA) 13: B3+ Al3+ Ga3+ Loses 3 electrons to form 3+ ions

Predicting Ionic Charges Group (IVA) 14: Many Group IVA (14) elements rarely form ions. Lose 4 electrons or gain 4 electrons?

Predicting Ionic Charges Nitride Group (VA) 15: Gains 3 electrons to form 3- ions P3- Phosphide As3- Arsenide

Predicting Ionic Charges Oxide Group (VIA) 16: S2- Sulfide Gains 2 electrons to form 2- ions Se2- Selenide

Predicting Ionic Charges F1- Fluoride Br1- Bromide Group (VIIA) 17: Gains 1 electron to form 1- ions Cl1- Chloride I1- Iodide

Predicting Ionic Charges Group (VIIIA) 18: Stable Noble gases do not form ions!

Predicting Ionic Charges Groups 3 - 12: Many transition elements have more than one possible oxidation state. Roman numerals are used to indicate the oxidation state Iron(II) = Fe2+ Iron(III) = Fe3+

Predicting Ionic Charges Some transition elements have only one possible oxidation state. Groups 3 - 12: Zinc = Zn2+ Silver = Ag+

Writing Ionic Compound Formulas Example: Iron(III) with chloride 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Fe3+ Cl- 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! Fe3+ Cl- 4. Name the ions 3 Balanced! Iron(III) chloride

Ba2+ NO3- ( ) Ba2+ NO3- 2 Example: Barium with nitrate Barium nitrate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Ba2+ NO3- 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) Ba2+ NO3- 4. Name the ions 2 Barium nitrate Balanced!

NH4+ SO42- ( ) NH4+ SO42- Your Turn! 2 Example: Ammonium with sulfate 1. Write the formulas for the cation and anion, including CHARGES! NH4+ SO42- 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) NH4+ SO42- 4. Name the ions 2 Ammonium sulfate

Al3+ S2- S2- Al3+ 3 2 Example: Aluminum with sulfide Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Al3+ S2- 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 4. Name the ions S2- Al3+ 3 2 Aluminum sulfide

Mg2+ CO32- Example: Magnesium with carbonate Magnesium carbonate 1. Write the formulas for the cation and anion, including CHARGES! Mg2+ CO32- 2. Check to see if charges are balanced. 4. Name the ions They are balanced! Magnesium carbonate

Zn2+ OH- ( ) Zn2+ OH- 2 Example: Zinc with hydroxide Zinc hydroxide 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Zn2+ OH- 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) 4. Name the ions Zn2+ OH- 2 Zinc hydroxide

Ca2+ PO43- ( ) Ca2+ PO43- 3 2 Example: Calcium with phosphate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Ca2+ PO43- 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 4. Name the ions ( ) Ca2+ PO43- Calcium phosphate 3 2